In smart meter system voltage and current sensing, electrical isolation between the high voltage and the low voltage domains is necessary. One common way to achieve that is to use voltage and current transformers. The average power dissipated in resistive loads, e.g. household appliances, can be calculated as the product of root-mean-squares of current and voltage averaged over a time period. But for non-resistive loads, such as AC motors, the average AC power can be calculated by the direct product of current and voltage averaged over a period of time. Since the voltage induced across a transformer is proportional to the rate of change of current, a direct measurement of the current cannot be easily done directly from the outputs of a current transform. On the other hand, a direct current sensing can be easily done by measuring the voltage drop across a small shut resistor connected in series with the power line. Another advantage of using resistors and optically coupled isolators is the fact that voltage and current sensing's cannot be tampered as in the case of transformers by placing a strong external magnets in the close proximity as to saturate the transformer cores. In addition, the transformer-less approach is the smaller size as compared with that of transformers to enable a compact form factor design. Furthermore, the cost of resistors and isolators are less as compared to that of the transformers.
There is a need to enhance system performance, reliability, testability and manufacturability of the smart meter during the product production and prototyping. Accordingly, what is needed is a system and method that addresses such needs. The system and method must be easily implemented, cost effective and adaptable to existing systems. The present invention addresses such a need.